Vinification, or converting grape juice into wine, is known to include multiple steps, in the course of some of which the grape juice is left to stand in receptacles for a certain period of time in order to obtain various effects.
Among the beneficial effects expected can be listed the enrichment of the juice above all with tannin, but also in aroma, as a consequence of changes that occur between the juice and the entire receptacle, when the receptacle is wooden, and in particular when it is made of oak or chestnut.
This enrichment generally improves the wine to be made.
Naturally this phenomenon of exchange with the wooden wall is exploited for making beverages other than wine; among them, whiskey, liqueurs, and so forth can be named.
Wooden receptacles are increasingly expensive, and they entail major problems in terms of upkeep.
Their cost is particularly due to the fact that their construction requires staves that can be made only from boards taken from the most valuable parts of the oaks or chestnuts.
As a result, some users have thought of replacing them with receptacles of neutral, non-oxidizable material, such as stainless steel or plastics.
Particularly with receptacles made of neutral material, their ease of cleaning and the fact that they enable rapid, controlled temperature variation appeared to be advantageous.
Despite these advantages, such receptacles prove unsuitable for use over the entire course of vinification, because of the loss of the contact with the wood.
To overcome this disadvantage, some beverage makers use tanks made of neutral material, and then wooden barrels, in succession over the course of vinification.
Although this solution has made it possible to obtain fairly good results, it is still no less burdensome, because it only partially solves the problem.
To retain the interactions with the wood without having to use wooden receptacles or wood as valuable as that required for the staves, the idea of immersing wood in the grape juice has already occurred to those skilled in the art.
For example, wood in the form of chips has been immersed, either freely or contained in a narrow, juice-permeable bag.
One of the disadvantages of this method is that the exchange surface of the chips cannot be monitored precisely.
In fact, for two bags of equivalent weight, the effective surface area of the chips may vary considerably depending on their size.
Furthermore, the chips break down into dust and contaminate the wine.
In an attempt to overcome this disadvantage, it has already been thought of to use wooden inserts such as veneers or slats that have an exchange surface that is more easily monitored than that of chips; but then the problem arises of keeping these elements properly placed in each receptacle, in particular to keep them below the level of the juice despite the fact that wood floats, and to keep them from moving in front of the inspection flap and thereby hindering the passage of sensors or other devices through it.
To overcome that disadvantage, it is known (French Patent A 2.504.498) to use a wooden insert of a size just slightly less than the volume of the container, which includes a certain number of elongated elements that before being inserted into the receptacle are assembled to form a compartmented structure, in which the sides of the compartments are accessible to the liquid in which the insert is immersed.
The disadvantage of this insert is that in order to introduce it into the container, the wall of the receptacle must be provided with an opening that has a cross section adapted to at least one of the cross sections of the insert, and hence is very large.
The problem then arises of the tightness of the plug, especially when it has to close the aforementioned cutout in a removable fashion.
Clearly, this insert cannot simply be enclosed at the time the receptacle is manufactured, because the insert wears out and must be replaced after virtually every phase of vinification.